The present invention described herein relates to semiconductor device technology and more particularly, to a semiconductor device incorporating a capacitor and a method of fabricating the same.
Capacitors using metal electrodes are regarded as suitable for applications requiring high frequency operation, rather than capacitors using polysilicon electrodes. The polysilicon electrodes have drawbacks caused by low capacitance by oxidation of parts that contact dielectric films and degradation of capacitance by generation of parasitic capacitance due to ionic depletion.
Metal-insulator-metal (MIM) capacitors are mostly employed in high-performance semiconductor devices because they have small resistivity, without depletion capacitance, and are suitable for high frequency operation.
FIG. 1 is a schematic diagram of a general conventional MIM capacitor.
Referring to FIG. 1, an MIM capacitor includes a bottom electrode 14 connected to a lower interconnection 12 included in a lower dielectric film 10. An inter-layer dielectric film 16 covers the bottom electrode 14. The bottom electrode 14 corresponds to a portion of multi-level interconnections in a semiconductor device.
The inter-layer dielectric film 16 is partially etched to expose the bottom electrode 14 in the capacitor region. A dielectric film 18 is conformably formed in the capacitor region. A metal with a good filling characteristic, such as tungsten (W), is provided on the dielectric film 18, forming a top electrode 20. The top electrode 20 is connected to an upper interconnection layer 22 covered by an upper dielectric film 24 formed on the inter-layer dielectric film 16.
As stated, a conventional MIM capacitor is characterized in a structure that the lower electrode is used with a portion of the interconnection layer and the top electrode fills the capacitor region. Thus, the dielectric film extends in area because it is formed on the sidewall and bottom of the capacitor region, but an effective area between the top and bottom electrodes 14 and 20 is relatively small. Although it is desirable to increase a planar area of the electrode, there is a limit to the amount of area that may be occupied by the capacitor in a semiconductor device.